Download Weather

Weather
Our World: What is Weather? video
What do you think of when someone says “weather?”
Questions from Bill Nye video
1. What causes wind?
2. What are two things that were mentioned by
Bill Nye that causes wind?
3. True or False. Cold air pushes up warm air.
Weather is the state of the atmosphere
at a specific time and place.
What drives Earth’s weather?
Includes such conditions as air
pressure, wind, temperature and
moisture in the air.
The Sun’s heat evaporates water into
the atmosphere forming clouds; water
returns to Earth as rain or snow; the
Sun also heats air.
Temperature is a measure of air
molecule movement.
What do you think???
1. When the temperature is high, how do the molecules in the air move?
Do you think it would feel warm or cold?
2. When the temperature is low, how do the molecules in the air move?
Do you think it would feel warm or cold?
The Sun’s energy causes air molecules
to move rapidly; temperatures are high
and it feels warm
When less of the Sun’s energy
reaches air molecules, they move less
rapidly and it feels cold.
Quiz
1. State of the atmosphere at a specific time and place, determined by factors
Including air pressure, amount of moisture in the air, temperature, wind, and
Precipitation is called _______________.
2. What drives the Earth’s weather?
3. What causes wind?
4. A measure of air molecule movement is called _______________.
5. If air molecules are moving rapidly, would you feel warm or cold?
6. If air molecules are moving slowly, would you feel warm or cold?
Wind –air moving in a specific
direction.
Why can you fly a kite on some days but not others?
Many instruments can be used to
measure wind direction and speed.
Wind Vanewind direction
Wind Sock-wind
direction
Anemometer-wind
speed
As the Sun heats air, it expands,
becomes less dense, rises, and has
low atmospheric pressure.
Cooler air is
denser and
sinks,
causing high
atmospheric
pressure.
Air moves from high pressure areas
to low pressure areas, causing wind.
What do you think “iso” means?
Use your textbook to look up the word isobar.
Humidity –the amount of
water vapor in the air.
Warmer air can hold more water vapor,
tending to make it more humid.
Relative humidity –the amount of
water vapor in the air compared to
what it can hold at a specific
temperature.
When air cools, it can’t hold as much
water vapor, so the water vapor
condenses to a liquid or forms ice
crystals.
Dew point- the temperature at which air
is saturated and condensation forms.
Quiz
1. What is the state of the atmosphere at a specific time and place?
2. What is a measure of air molecule movement?
3. Air moving in a specific direction is called _____________.
4. Warm, expanding air has (high/low) pressure.
5. Cold, sinking air has (high/low) pressure.
6. Instrument used to determine wind direction is called a ________ ______.
7. Wind speed is measured using an ________________.
8. Air moves from _________pressure areas to _________pressure areas.
9. __________ is the amount of water vapor in the air.
10. The temperature at which air is saturated and condensation forms is called the _________
__________________.
Clouds form as warm air is forced
upward and cools. then the water
vapor condenses in tiny droplets that
remain suspended in the air.
Cloud
Video
The shape and height of clouds vary
with temperature, pressure and the
water vapor in the atmosphere.
In 1803, Luke Howard classified clouds using Latin terms cirrus, cumulus, stratus,
And nimbus.
Now using a dictionary , look up the following words:
1.Cirrus
2.Cumulus
3.Stratus
4.Nimbus
Cloud Shape

Stratus: smooth, even sheets or layers at low
altitudes.
Cloud Shape

Cumulus: puffy, white clouds, often with flat
bases.
Cloud Shape

Cirrus: high, thin,
white feathery clouds
made of ice crystals.



Cloud Height
Cirro: high clouds
Alto: middle-elevation clouds
Strato: low clouds
Nimbus clouds are dark and so full
of water that sunlight can’t penetrate
them.
Clouds
Stratus Clouds-Very little precipitation from most stratus clouds
-Two types of stratus clouds: Nimbostratus (heavy precipitation)
Altostratus (very little precipitation)
Cumulus Clouds- Associated with fair weather or
thunderstorms
-cumulonimbus clouds or thunderheads are accompanied by
rain, lighting & thunder
Cirrus Clouds-associated with fair weather but
they can indicate approaching storms.
-Cirrocumulus clouds appear just before snowfall or rainfall
Precipitation: water falling from
clouds.
When water droplets in clouds
combine and grow large enough
precipitation falls to Earth.
Air temperature determines whether
droplets form rain, snow, sleet, or
hail.
Now do the Section 1 Review Questions found in your
textbook on page 574.
Do questions #1, 2, 3, 4, 5, and 6
Section
2:
Weather
Patterns
Mr. Parr wind song review
Because air and moisture move in
the atmosphere, weather constantly
changes.
Air mass –large body of air with
properties like the part of Earth’s
surface over which it is formed.
Highs and Lows

Stormy weather is associated with low pressure
areas.

Fair weather is associated with high pressure
areas.

Air pressure is measured by a barometer.
Front –a boundary between two
different air masses.
Clouds, precipitation, and storms
occur at frontal boundaries.
Cold front- where colder air advances
under warm air.
Warm front –where warmer air
advances over colder air
Occluded front –involves three air
masses of different temperatures.
Stationary front –air mass and their
boundaries stop advancing.


Warm, moist air is forced rapidly upward, where
it cools and condenses.
Strong updrafts of warm air and sinking, raincooled air cause strong winds.
Mr. Parr
Front song
Thunderstorms occur inside warm,
moist air masses and fronts.
Tornado footage
Weather 101
Lightning


Movement of air inside a storm cloud causes
parts of the cloud to become oppositely
charged.
Current flows between the regions of opposite
electrical charge, forming a lighting bolt.
How lightning
Forms?
How lightning
Works discovery
Channel 5 min
Thunder –lighting superheats the air,
causing it to expand rapidly and then
contract, forming sound waves.
Tornado –a violent, whirling wind that
moves in a narrow path over land.
How
Tornado
form
Hurricane –a large, swirling, lowpressure system that forms over
How Hurricanes work
tropical oceans.
Blizzard – a winter snow storm with
strong winds, cold temperatures, and low
visibility, that lasts more than three hours.
Severe Weather Safety


A National Weather Service watch means
conditions are favorable for severe weather to
develop.
A warning means that severe weather conditions
already exist.
Section 3: Weather Forecasts
Meteorologists study and predict the
weather.
The National Weather Service makes
weather maps.
Station models show weather
conditions at a specific location.
Temperature and Pressure

Isotherms are lines on
a weather map
connecting points of
equal temperature.

Isobars are lines on a
weather map that
connect points of
equal atmospheric
pressure.
Weather fronts move from west to east.